tough nut to crack—(also: hard nut to crack)
1. a difficult person to deal with:
- Meggie was going to be a tough nut to crack and he couldn’t afford to frighten her.
2. a difficult problem or task to undertake:
- Getting them all here on time will be a tough nut to crack.
tough row to hoe —(also: hard row to hoe) = tough nut to crack 2:
- Getting the contract signed is going to be a tough row to hoe.
Note: Neither expression correlates in meaning with the phrase tough act to follow—(also: hard act to follow) used of an outstanding individual or a particularly good performance that will be difficult to emulate:
- The gifts, the decorations, the food—everything was exacting and amazing. It will be a tough act to follow.